Abstract

In this study, we report on the three-dimensional (3D) characterization of a spray in terms of its droplet Sauter mean diameter (SMD) using the laser-induced fluorescence (LIF)/Mie ratio technique. The spray structure is analyzed for a multi-hole direct-injection spark ignition (DISI) injector. A calibration curve to convert the LIF/Mie ratio to droplet diameter is deduced using LIF/Mie imaging and analysis of single droplets generated by a droplet generator. The DISI spray investigated here is optically sectioned by means of two-phase structured laser illumination planar imaging to suppress the intensity of multiple light scattering from LIF and Mie images prior to their ratio. A series of calibrated LIF/Mie ratio images of spray is then recorded at several depths along the $z$ direction following the light sheet scanning of the spray. The droplet SMD ranges from less than 5 μm up to a maximum of 50 μm in single-shot images. The averaged SMD results (1–30 μm) obtained by using the calibration curve from the droplet generator are compared with measurement results from phase-Doppler anemometry. Finally, a 3D map is reconstructed from the successive 2D layers generated from spray scanning. The resulting 3D representation of the droplet SMD shows a non-symmetric spray structure produced by the studied multi-hole injector, which cannot be resolved by analyzing only one central plane.

© 2019 Optical Society of America

Analysis of LIF and Mie signals from single micrometric droplets for instantaneous droplet sizing in sprays

Matthias Koegl, Bernhard Hofbeck, Kevin Baderschneider, Yogeshwar Nath Mishra, Franz J. T. Huber, Edouard Berrocal, Stefan Will, and Lars Zigan
Opt. Express 26(24) 31750-31766 (2018)

Reliable LIF/Mie droplet sizing in sprays using structured laser illumination planar imaging

Yogeshwar Nath Mishra, Elias Kristensson, and Edouard Berrocal
Opt. Express 22(4) 4480-4492 (2014)

The Determination of the Sauter Mean Droplet Diameter in Fuel Nozzle Sprays

R. H. Dieck and R. L. Roberts
Appl. Opt. 9(9) 2007-2014 (1970)

Polarization-dependent LIF/Mie ratio for sizing of micrometric ethanol droplets doped with Nile red

Matthias Koegl, Hongfei Dai, Kevin Baderschneider, Hannah Ulrich, and Lars Zigan
Appl. Opt. 61(14) 4204-4214 (2022)

Laser sheet dropsizing based on two-dimensional Raman and Mie scattering

Anna Malarski, Benedikt Schürer, Ingo Schmitz, Lars Zigan, Alexandre Flügel, and Alfred Leipertz
Appl. Opt. 48(10) 1853-1860 (2009)